docs: def contains(self, val):
  
          """
          Check if given value or range is present.
  
          Parameters
          ----------
          val : int or tuple or list or range
              Range or integer being checked.
  
          Returns
          -------
          retlen : int
              Length of overlapping with `val` subranges.
          """
  
          (start, end) = self.__val_convert(val) # conversion
  
          retlen = 0
          for r in self.__has:
              if start < r[1] and end > r[0]:
                  retlen += ((end < r[1] and end) or r[1]) - ((start > r[0] and start) or r[0])
  
          return retlen